Electrical characterization of GaN metal oxide semiconductor diodes using MgO as the gate oxide

GaN metal oxide semiconductor diodes were demonstrated utilizing MgO as the gate oxide. MgO was grown at 100°C on MOCVD grown n-GaN in a molecular beam epitaxy system using a Mg elemental source and an electron cyclotron resonance oxygen plasma. H₃PO₄ based wet-chemical etchant was used to remove MgO to expose the underlying n-GaN for ohmic metal deposition. Electron deposited Ti/Al/Pt/Au and Pt/Au were utilized as ohmic and gate metallization, respectively. An interface trap density of low-to-mid 10¹¹ eV^-1cm^-2 was obtained from temperature conductance-voltage measurements. Terman method was also used to estimate the interface trap density and a slight lower number was obtained as compared to the conductance method. Results from elevated temperature (up to 300°C) conductance measurements showed an interface state density roughly three times higher(6×10¹¹ eV^-1 cm^-2) than at 25°C.